Rainbow Electronics AT42QT1110-AZ - Manual (Page 13)

13
9570H–AT42–02/10
AT42QT1110-MZ/AT42QT1110-AZ
For example, Figure 4-3 on page 12 shows the exchange that takes place to read the 2-byte “All
Keys” report. In this exchange, the host sends:
0xC1 — 0x00 — 0x00
and the QT1110 returns (simultaneously):
0x55 — Report Byte 0 — Report Byte 1
If CRC is enabled, this exchange is extended to 5 bytes, as shown in Figure 4-4 .
Figure 4-4. All Keys Report – CRC Enabled
4.1.5.1 Set Instructions
Set Instructions are 2-byte transmissions by the host that are used to send settings to individual
locations in the device memory map.
At the first byte, the QT1110 returns 0x55 (“Idle”) to confirm that it will interpret the byte as a new
command. At the second byte, the QT1110 returns the “Set” command it has just received.
For example, to set the “Positive Recalibration Delay” to 1920 ms, address 5 in the memory map
is set to 12 (0x0C). This is done with the “Set” command for address 5 (command code 0x95),
as shown in
Figure 4-5 on page 14 .
Host (Sends on MOSI)
Command: 0xC1
Null: 0x00
Key Status Report Byte 0
Null: 0x00
Key Status Report Byte 1
Null: 0x00
Report CRC: 0x??
Simultaneous
Transmission
Command CRC: 0x94
Response: 0x94 (Expected Command CRC)
Response: 0x55 ( Idle” Fresh Command) “ –
Device (Responds on MISO)